Brush holder



June 26, 1923.

R. E. HELLMUND BRUSH HOLDER Filed July 30, 1920 I N V E N T O R 72 E/Z/zzzzzzza.

WITNESSES:

AT-TORNEY Patented June 26, 1923.

UNITED STATES PATENT OFFICE.

BUDOLF E. HELLMUND, F SWISSVALE, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELEGTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

BRUSH HOLDER.

Application filed July 30, 1920. Serial No. 400,145.

To all whom it may concern:

Be it known that LR-unonr E. HELLMUND, 13/ citizen of the United States, and a resident of Swissvale, in the county of Allegheny and State of Pennsylvania, have invented a new i and useful Improvement in Brush Holders, of which the following is a specification.

My invention relates to brush-holders and particularly to devices for suppressing or eliminating flashing-over of commutator cylinders, especially on apparatus having very severe'commutating conditions, such,

for example, as railway motors.

Heretofore, in railway-motor construction,

,great difficulty has been encountered in preventing the occurrence of flash-overs from the commutator to other parts of the machine. It is practically impossible to prevent the carbon brushes from occasionally jumping out of contact with the commutator cylinder, thereby establishing an arc therebetween. Such arcs are also formed, at times, at the toe of the carbon by numerous other causes.

If an arc remains near the place of its formation, until the disturbing conditions have disappeared, no damage is done thereby. If, on the contrary, the arc is directed or attracted away from this place by air draughts or stray magnetic fluxes, it usually results in a series of flashings and resultant damage tothe machine.

One of the objects of my invention is to provide a path of relatively high magnetic conductivity whereby the stray magnetic fluxes, above referred to, will be so concentrated and confined to a predetermined locality far enough removed from the point of contact between the brushes and the commutator as to have little or no influence upon an are formed therebetween.

Another object is to construct a conductor for the magnetic fluxes referred to that will also shield an are from being diverted by air draughts that may be present.

' In the accompanying drawings:

Fig. 1 is a fragmentary view, partly in elevation andpartly in section, illustrating a preferred embodiment of my invention.

Fig. 2 is a fragmentary sectional view through a brushholder on line II-II of v Fig. 1.

Fig. 3 is a bottom plan view of a conduc tor constructed inaccordance with my in vention.

Fig. 4 is a front elevational view of a brushholder embodying a modified form of my invention.

Fig. 5 is a fragmentary sectional view on line IV-IV of Fig. 4.

Referring to the drawings, a shaft '1 is journaled in a bearing 2 supported on the frame or casing 3 of a dynamo-electric machine. The shaft 1 carries an armature 4 having a commutator 5 of usual construction and coacting with a stator field coil 6. A brush-holder 7 is secured'to the frame 3, in any preferred manner, and is provided with a plurality of carbon brushes 8 for contact with the commutator 5.

A rectangular conducting element 9, preferably formed of material having a relatively high coefficient of magnetic conductivity, such as soft iron or annealed iron casting, surrounds the brushholder 7 adjacent the lower portion thereof and is secured thereto by means of screws 10 at a point in proximity to the cylinder 5. The conducting element 9, preferably comprising side members 11 and end members 12' and 13', is so arranged as to lie in a field of stray magnetic fluxes F existing between the stator coil 6 and the frame 3 of the machine in the vicinity of the point of contact between the brushes 8 and the commutator cylinder 5. By this arrangement, the fluxes F, following the path of least resistance, are collected and confined to a particular locality remote from the point of contact between the brushes and the commutator cylinder. These ordinarily disturbing lines of force are thus prevented from influencing or diverting an are that may be formed by the brushes jarring out of contact with the commutator cylinder. y

In order that all deflecting air currents may be effectively excluded fromthe arcing locality, the end member 12 of the conductor element is extended downwardly, asat 14, past the edge of the commutator cylinder and shields the same against the diverting action of air currents. The end portion 13 is preferably so cut away, as at 15, as to form a relatively flat extension which overhangs the commutator cylinder and diverts any currents of air that may blow from that direction. The side portions 11 of the conductor, owing to the curvature of the commutator cylinder, extend downwardly to points adjacent the toe of the brush 8 (Fig. 2) and protects the same from lateral air currents.

A substantially U-shaped member 16, of insulating material, is secured to the arm of the brushholder, in any preferred manner, at a point substantially contiguous with one of the membersll. y this arrangement, the creepage distance is increased from the toe of the brush to the handle of the brushholder, and an arc is thus prevented from jumping to, and travelling along, the same.

In Figs. 4'and 5, I have shown a modified form of my invention wherein a brushholder 7 is formed with arallel horrizontally disposed apertures within which two soft iron bars 9' are secured. This construction, while requiring a special form of brushholder, constitutes a compact structure and eliminates any possibility of the bars 9 from being accidentally displaced.

The above means is very effective in eliminating magnetic-blow fields near the arc. Instead of eliminating such fields entirely, it is, of course, possible to employ fields purposely and arrange them to blow in the proper direction so that an are that may e formed cannot reach any undesirable parts of the machine. Another possibility is to arrange magnetic fields of opposite direction at both sides of the carbon brush of such polarity that it is always thrown back by the magnetic fields to its original location, regardless of the diverting tendency of possible air currents. I

I claim as my invention:

1. A brushholder adapted to maintain a brush in co-operation with a commutator cylinder and provided with means for protecting an are formed between the brush and the commutator cylinder against defiection.

2. A brushholder adapted to maintain a brush in co-operation with a commutator cylinder and provided with means for protecting an are formed between a brush and the commutator cylinder against the diverting action of magnetic fluxes.

3. A brushholder adapted to maintain a brush in co-operation with a commutator cylinder and provided with means for protecting an are formed between the brush and the commutator cylinder a ainst the defleeting action of air currents directed there.- against. a

4. A brushholder adapted to maintain a brush in co-operation with a commutator cylinder and having magnetic means for preventing the diverting of an are formed between the brush and the commutator cylinder.

5. A brushholder adapted to maintain a brush in co-operation with a commutator with, and means carried by said brush- Y holder adjacent to said cylinder for divert.- ing magnetic fiuxes from said point of contact.

8. A brushholder adapted to maintain a brush in co-operation with a commutator cylinder and having magnetic means for diverting stray magnetic fluxes from the place of contact of the brush with the commutator cylinder. 1

9. A dynamo-electric machine having, in combination, a commutator, a brushholder adjacent said commutator, a brush held in said holder for contact with said commutator and means whereby magnetic fluxes are diverted from the point of contact between said brush and said commutator.

10. A dynamo-electric machine having, in combination, a commutator, a brushholder adjacent said commutator, a brush held in said holder for contact with said commutator and means whereby magnetic fiuxes existing in the vicinity ofsaid point of contact are concentrated at a locality remote therefrom.

11. A dynamo-electric machine havin ,in combination, a commutator, a brushho der adjacent said commutator, a brush held in said holder for contact with said commutator, and means whereby magnetic fluxes are caused to be concentrated and traverse a definite path remote from said point of contact.

12. A dynamo-electric machine having, in combination, a commutator cvlinder, a brushholder adjacent thereto, a brush held in said holder for contact with said commutator and means for substantially preventing the flow of magnetic fluxes across said point of contact.

13. A dynamo-electric machine having, in combination, a commutator cylinder, a brushholder adjacent thereto, a brush held in said holder for contact with said cylin der and a conductor having a relatively high co-eflicient of magnetic conductivity so arranged as to divert magnetic fluxes from said point of contact.

14. A dynamo-electric machine having, in'combination, a commutator cylinder, a

brushholder adjacent thereto, a brush held surface of the cylinder and so arranged as in said holder for contact with said comto divert magnetic fluxes from said point of mutator and a member so arranged as to contact.

divert magnetic fluxes from said point of 16. In a dynamo-electric machine, mag- 15 5 contact. netic means for confining an are formed be- 15. A dynamo-electric machine having, tween a brush and the commutator cylinder in combination, a commutator cylinder, a to the neighborhood of its origin.

brushholder adjacent thereto, a brush held In testimony whereof, I have hereunto in said holder for contact with said cylinsubscribed my name this 20th day of July, 20 10 der a pluralit of conductors carried by 1920.

said holder an extending parallel with the RUDOLF E. HELLMUND. 

